Suspension for compasses and other instruments



Aug. 17, 1937. A. ZIMMERMANN n 2,090,564

SUSPENSION FOR COMPASSES AND OTHER INSTRUMENTS Filed Sept. 5; 1934 2 Sheets-Sheet 1 Fig.1

A. ZIMMERMANN 2,090,564

SUSPENSION FOR COMPASSES AND OTHER INSTRUMENTS Filed Sept. 5, 19:54 2 Sheets-Sheet 2 Inventor.-

Patented Aug. 17, 1937 UNITED STATES SUSPENSION FOR COMlASSES AND HER INSTRUIVIENTS August Zimmermann, Berlin-Steglitz, Germany,

assignor to Askania-Werke A. G.

vormals Centralwerkstatt-Dessau und Carl Bamberg- Friedenau, a corporation of Germany Application September 5, 1934, Serial No. 742,795

' In Germany September 18, 1933 '7 Claims.

This invention relates to compasses and other instruments, used more particularly in aircraft, and one of the objects of the invention is to provide a mounting or suspension for such instruments which shall protect them from vibrations, more particularly those of periodicity and high frequency.

This and other objects and aims of the inven tion will be readily understood from the following description, taken in connection with the accompanying drawings of one embodiment of the invention herein given for illustrative purposes, the true scope of the invention being more particularly pointed out in the appended claims.

In the drawings;

Fig. 1 is a partly diagrammatic lateral elevation of one illustrative embodiment of the invention, certain parts being shown in section, and

Fig. 2 is a partly diagrammatic top plan view of the illustrative embodiment of the invention shown in Fig. 1, certain parts being shown in section.

An illustrative embodiment of the invention will now be described in its application to compasses, but it will be understood that the invention is equally applicable toother sensitive instruments for use more particularly in aircraft, such as rate of climbindicators etc.

Referring to the drawings, 2- is the compass bowl which is closed by a dome-shaped glass cover 4. At the junction of said bowl and cover a ring 6 provides a tight closure between said bowl and cover. Said bowl is provided at its base with a cylindrical extension 8 upon which is 5 firmly clamped a clamping ring Ill.

Supporting means is provided for the instrument} said means herein illustratively comprising an inner supporting member I2, herein a ring of general conical cross section and screwed or 40 otherwise firmly securedto said ring III, as clearly shown in Fig. 1. Surrounding said inner member I2 there is provided an outer, similar supporting member I4 which, in accordance with the invention, will preferably also be of general con- 45 ical cross section. Said outer member I4 may be rigidly secured in any suitable manner to a bracket I6 or may be integral with the latter, said bracket being adapted to be secured. to the instrument board or other suitable conveniently 50 situated fixed portion of the aircraft.

The invention contemplates the provision of means to absorb or damp vibrations which may be caused by shocks or vibrations to which the compass or other instrument may be subjected, more 56 particularly from the outside. It is well known that the vibrations engendered in aircraft have a disturbing, injurious action upon compasses, rate of climb indicators and other sensitive instruments-used with aircraft, in that the instrument is thereby subjected to vibrations or oscillations 5 which keep the indicating means of said instrument, the needle of a compass for example, in a state of unrest by causing it to oscillate. This results in false indications and readings and may even cause damage to the instrument. The presl0 entinvention aims to protect the instrument from such vibrations, thusgobviating the objections referred to and ensuring correct indications or readings. Preferably said vibration absorbing or damping means will be provided between said 1 inner member I2 and said outer member I4, and will preferably comprise a plurality of resilient devices I6 disposed circumferentially of said inner member I2 and at an angle to the radii of said member. To this end said devices I6 are 20 secured at their opposite ends to said member l2 and said member I4 respectively, the points at which they are secured to one of said members being staggered relatively to the points at which they are secured to the other of said members. 25 Herein said resilient devices conveniently comprise a plurality of sections of a band or cord of rubber or other resilient material, which having its two free ends it and 2ll. secured in adjacent openings 22 and 24 in one of said members, 30

member I4 for example, extends about said member I2 passing through sets of two adjacent openings 26 and 28 provided alternately in the one and the other of said members I2 and I4. The points of connection of said resilient means or devices to said member I4 and to the instrument respectively being thus laterally spaced from each other about the instrument. It will be noted therefore that said sections I6 are disposed or extend obliquely between said two members I2 and I4. This angular or, oblique arrangement of said resilient devices or sections i6 en-. ables them to be made of a sufiicient size or length to ensure an efiicient damping action which shall sufiice to protect the instrument from the injurious vibrations above referred to, and this without increasing the size of the instrument,

as would be necessary were said resilient devices or sections I6 disposed radially. If said resilient devices or sections were disposed radially of said members I 2 and I4, it would be necessary in order effectively to meet the requirements that they be so longas to entail an increase in the transverse diameter of theinstrument that would so increase its bulk as to render it impracticable, pars5 ticularly for aircraft where a saving in both weight and space is important. Radially disposed resilient devices or sections sumciently short to keep the bulk of the instrument within practicable limits would not sumce to secure the desired results.

' Said resilient band or. cord of rubber may be secured to said members i4 and i2 in any suitable manner but the manner of securing herein used as above set forth is simple and has the ad-- vantage that where said band passes through the two adjacentopenings, said band forms a sharp almost rectangular kink, thus preventing" any displacement of the compass relatively to said band and ensuring that the compass when once placed in correct position on the aircraft shall retain said position.

Preferably two damping or vibration absorbing means will be used, and these will preferably be located in different horizontal planes. shown in Fig. 1 wherein a second rubber band 30 is illustrated in a plane below that of the rub her band i6. Said second band 30 may, and preferably is similar to said band It and may be secured to said members l4 and I2 in the same manner, its function being the same as that of said band It; It will be noted however that its sections are shorter than those of band It as it is connected to the part of less diameter of said two conical members i2 and M. It will be apparent that a spring could be used in place of said rubber band. Preferably reinforcing means, such as plates 32 and 34 will be used where said perforations 26 and 2B are provided in the members l2 and I4.

' A graduated ring 36 for compensating the error A may be provided upon the clamping ring Ill, and said members l2 and M will preferably be provided with openings 38 for the observation and adjustment of said graduated ring 36.

It will bev seen that the compass in the member I2 is held in suspension by the damping or vibration absorbing means, herein illustratively comprising the resilient elements or sections it.

The effective characteristics of said damping or vibration eliminating means, that is to say the length strength and initial tension, and so forth of the resilient bands or cords in the illustrative embodiment of the invention described, will preferably be so selected and predetermined that the natural frequency of the suspended compass or other system relatively to the upper damping means or band and to the lower damping means or band respectively, shall bear such a relation to each other that resonance oscillations or vibrations cannot occur. In this way all vibrations will be eliminated, any vibrations produced by a shock and that might penetrate through one of said damping means or bands, will inevitably be damped or eliminated by the other damping means or band. In the illustrative embodiment of the invention described this result may be secured by making both bands initially of the same strength and preliminary tension while making the sections of said bands of different lengths. This is conveniently eflected'in the illustrative embodiment of the invention described, by the Preferably also the effectivecharacteristics of said damping means or bands, which determine the natural frequency of the suspended system relatively to said damping means, will be This is conveniently'consist for example of a damping layer 42 of sponge rubber or the like, mounted between said two members I2 and I4.

The conical cross sectional shape of said memhers I 2 and ll and the provision of the two-damping means in different, relatively widely spaced horizontal planes, also prevents tipping of the compass.

I am aware that the invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and I therefore desire the present embodiment of the invention to be considered in all respects as illustrative and not restrictive, reference being had to the appended claims rather than to the foregoing description to indicate the scope of the invention.

I claim:-

1. Suspension for compasses and other instruments, more particularly for aircraft, comprising, in combination, an instrument supporting ring and a second ring surrounding said first named ring, each of said rings being provided with ,a plurality of perforations disposed in pairs, the

pairs of perforations in one ring being in staggered relation in the pairs of perforations in the other ring; and a flexible resilient member threaded through the perforations of said rings.

2. Suspension for compasses and other instruments, more particularly for aircraft, comprising,

in combination, an instrument supporting ring and a second ring surrounding the same, each of said rings provided with a plurality of perforations disposed in pairs, the pairs of perforations in one ringvbeing in staggered relation to the pairs of perforations in the other ring; and a rubber band threaded through the perforations of said rings.

3. A suspension for compasses or other instruments, comprising a ring carried by and surrounding the instrument; a second ring surrounding said first-mentioned ring and spaced therefrom, said second ring being adaptedto be secured in fixed position; resilient members and means to connect said resilient members to the said rings, the-points of connection of said resllient'mem'bers to said two rings respectively being laterally spaced from each other about the instrument.

- 4. A suspension for compasses or other instruments comprising a ring carried by and surrounding the instrument; a second ring surrounding and spaced from said first-mentioned ring and adapted to be secured in fixed position; resilient members disposed in two substantially horizontal planes; and means to connect said resilient members to the said rings, the points of connection of said resilient members to said two rings respectively being laterally spaced from each other about the instrument.

5. A suspension for compasses or other instruments comprising a ring of substantially conical cross section carried by and encircling the injstrument; a second fixed ring of substantially conical cross section surrounding and spaced from said first-mentioned ring; resilient mom bers disposed in two substantially horizontal planes; and means to connect said resilient members to said rings, the points of connection of said resilient members to said two rings respec- 5 tively being laterally spaced from each other about the instrument, and said resilient members in one plane being of different length from said resilient members in the other plane.

6. A suspension for compasses or other instru- 10 ments comprising an interior annular support for the instrument carried by and surrounding the latter; and an exterior support surrounding said interior support and adapted to be secured in fixed position, each of said supports being pro- 15 vided in two substantially horizontal planes with a plurality of perforations disposed in pairs, the pairs of perforations in each plane in said interior support being arranged in staggered relation to the pairs of perforations in the same 20 plane in said exterior support; and a rubber band threaded through the perforations of said supports in each plane.

7. v A suspension for compasses or other instruterior supports.

ments comprising an interior annular, ring shaped support of substantially conical crosssec-- tion carrying and surrounding the instrument; an exterior ring shaped support of substantially conical cross section surrounding said interior support and adapted to be secured in fixed position, each of said supports being provided in two substantially horizontal planes with a plurality shorter than the portions of the rubber band extending between the perforations of said supports in the other plane; and a layer of porous resilient material between said interior and ex- AUGUST ZIMIMERMANN, 

